Septal defects are a relatively common occurrence. While many septal defects are relatively benign and have little or no impact on a person's health, other septal defects can be more serious.
One type of septal defect is a patent foramen ovale (PFO), which is an opening between the right atrium and the left atrium. Because the fetal lungs do not provide air prior to birth, fetal blood is oxygenated by the mother via the umbilical cord and placentia. To provide for such circulation, the fetal blood circulation system includes several vessels and openings that remain open during fetal development but that close soon after birth. One such opening is the foramen ovale, which permits blood to flow from the right atrium into the left atrium in a fetal heart, thereby allowing blood to bypass the fetal lungs and flow directly from the venous circulation to the arterial circulation.
After birth, the infant's lungs typically provide oxygenation to the blood, and it is generally undesirable to continue having blood flow from the venous circulation to the arterial circulation without first passing through the lungs. Accordingly, it is generally desirable that the foramen ovale be closed after birth.
At birth, left atrial pressure increases as the pulmonary circulation is established. For most newborn infants, this pressure increase causes the closure of a flap of tissue which occludes the foramen ovale and then heals in the occluded position shortly after birth. In a significant percentage of persons, however, the tissue flap does not heal to permanently occlude the foreman ovale. This condition is known as a patent (i.e., open) foramen ovale (PFO).
While a PFO can be a relatively benign condition, PFOs have been associated with migraines. PFOs can also cause strokes by permitting blood containing small thrombi to bypass the lungs (which would otherwise filter out such small thrombi) and flow directly from the venous circulation to the arterial circulation and into the brain.
Treatments for PFOs range from open-heart surgery to percutaneous procedures. Open-heart surgery for PFOs typically involves suturing the PFO closed. Although relatively simple, such open-heart surgical treatment is associated with all the usual risks of cardiac surgery. Percutaneous methods include deploying mesh, clamshell, or other similar implanted devices to close the PFO. Other treatments include using heat, laser, RF, or other energy to treat the tissue of (or adjacent to) the PFO to induce the tissue to permanently close the PFO. Many of these percutaneous methods are often complicated and may involve relatively large implanted devices or uncertain tissue treatments.
One particularly effective method for repairing a PFO involves the percutaneous introduction of a catheter having a needle and suture assembly, with the suture percutaneously passed, via one or more needles deployed via the catheter, through the tissue surrounding the PFO. The catheter is withdrawn and the user tightens the suture to assess whether the suture has been deployed to properly close the PFO. The suture is then secured via tying or clipping, and the excess suture is cut and removed. The PFO is thus held closed by the tightened suture. Such a method and apparatus is disclosed in co-pending U.S. patent application Ser. No. 11/174,143, filed Jun. 30, 2005, the entire contents of which are expressly incorporated herein by reference. Other methods, systems, and devices for deploying suture that may be applicable for use with the current invention are disclosed in Applicant's U.S. Pat. Nos. 6,537,290; 6,626,930; 6,860,890; 6,719,767; 7,011,669; 7,083,628; and 7,094,244; and also in Applicant's co-pending U.S. application Ser. Nos. 10/233,879 and 10/389,721; the contents of each of which are incorporated in entirety herein by reference.
In light of the foregoing, there is presently a need for improved systems for treating PFOs. More specifically, there is a present need for an improved method, apparatus, and system for repairing PFOs. The current invention meets this need.